Determination of volatile organics in drinking water with USEPA method 524.2 and the ion trap detector

New drinking water regulations require the monitoring of eight volatile organic compounds that have established maximum contaminant levels (MCLs) and 51 other volatile organics for which MCLs are not established. A laboratory analytical method (Method 524.2) for the determination of 58 of these compounds is investigated, and precision and accuracy data are obtained. The method uses a standard inert gas purge extraction, isolation of the volatile organics on a three-stage solid-phase trap, thermal desorption into a gas chromatograph, separation with a fused-silica capillary column, and identification and measurement with a relatively low cost, benchtop ion trap detector that functions as a mass spectrometer. At a concentration of 2 micrograms/L (2 parts per billion), the grand mean measurement accuracy for 54 compounds was 95% of the true value with a mean relative standard deviation (RSD) of 4%. At 0.2 micrograms/L (200 parts per trillion), the grand mean measurement accuracy for 52 compounds was 95% of the true value with a mean RSD of 3%.     

Osmose

Ohne Zusammenfassung     

Entwicklung eines rechner-betriebssystems für die labordatenerfassung

The development of a computer operational system for data acquisitionAn operational controller, run on an IBM System/7, has been developed and tested for analytical data acquisition. This control system is particularly satisfactory with high external interrupt rates. It is based on self-synchronization of the analog—digital converters. The synchronization cycles serve as the trigger for various functions, e.g. for data transfer to the host computer. The interrupt servicing is done intermediately in an asynchronous manner.     

Tunable intramolecular multicenter H-bonding interactions in first-row metal complexes bearing bidentate redox-active ligands

Abstract

In this research article, we report the synthesis and structural characterization of a family of first-row metal complexes bearing redox-active ligands with tunable H-bonding donors. We observed that these coordination complexes can adopt three different geometries and that they are stabilized by intramolecular multicenter H-bonding interactions, which are systematically modified by changing the metal ion (Co, Ni, Cu, Zn), the ligand scaffold (variations in the diamine and ureanyl substituents used) and the solvent of crystallization.